Role of CD80 in stimulating T lymphocyte activation

AIM： To observe biological characteristics of hepatocarcinoma cells before and after CD80 transfection and to compare the effect of CD80-transfected hepatocarcinoma cells on T lymphocyte activation. METHODS： Retro virus vector carrying CD80 gene was transfected into HepG2 cells to establish CD80transfected hepatocarcinoma cells （HepG2/hCD80）. Flow cytometry （FCM） was performed to detect CD80 expression in the transfected cells. RT-PCR was used to evaluate CD80 expression at mRNA level. In the presence of anti-CD3 mAb, the proliferation of T lymphocyte was observed by M＇n＇. Meanwhile, the expression of activated molecule marker CD25 was analyzed through FCM. RESULTS： A stable cell line HepG2/hCD80 expressing the human CD80 was established. Growth curve showed that the molecule CD80 could obviously decrease the growth of tumor cells. HepG2/hCD80 was evidenced to have a potency to enhance T cell proliferation and upregulate CD25 expression. CONCLUSION： CD80 transfection can lower malignant phenotype of hepatocarcinoma cells. CD80 transfection has a down-regulatory effect to activated T cells in vitro.

Study on Lymphocyte Activation and Proliferation Induced by Anti-CD3 McAb

T cell activation and proliferation via CD3-TCR complex were investigated by lymphocyte DNA synthesis in vitro.Several interfering factors were also discussed.The result indicated that lymphocyte activation and proliferation are calciumdependent.A rise of cytoplasmic free Ca2+ quickly following activation with CD3 McAb is mainly due to intracellular mobilization of Ca2+,while lymphocyte proliferation needs both intracellular mobilization of Ca2+ as well as influx of extracellular Ca2+, It was confirmed that CTX sensitive G protein plays a role in regulating T cell proliferation by pretreatment with CTX suppressing lymphocyte H-TdR incorporation obviously.PLC and PKC inhibitor neomycin and P.S.S could also decrease T cell proliferation.

Long chikungunya?An overview to immunopathology of persistent arthralgia

Chikungunya fever(CF)is caused by an arbovirus whose manifestations are extremely diverse,and it has evolved with significant severity in recent years.The clinical signs triggered by the Chikungunya virus are similar to those of other arboviruses.Generally,fever starts abruptly and reaches high levels,followed by severe polyarthralgia and myalgia,as well as an erythematous or petechial maculopapular rash,varying in severity and extent.Around 40%to 60%of affected individuals report persistent arthralgia,which can last from months to years.The symptoms of CF mainly represent the tissue tropism of the virus rather than the immunopathogenesis triggered by the host's immune system.The main mechanisms associated with arthralgia have been linked to an increase in T helper type 17 cells and a consequent increase in receptor activator of nuclear factor kappa-Βligand and bone resorption.This review suggests that persistent arthralgia results from the presence of viral antigens post-infection and the constant activation of signaling lymphocytic activation molecule family member 7 in synovial macrophages,leading to local infiltration of CD4+T cells,which sustains the inflammatory process in the joints through the secretion of pro-inflammatory cytokines.The term"long chikungunya"was used in this review to refer to persistent arthralgia since,due to its manifestation over long periods after the end of the viral infection,this clinical condition seems to be characterized more as a sequel than as a symptom,given that there is no active infection involved.

Influence of REV and ALV-J Co-Infection on Immunologic Function of T Lymphocytes and Histopathology in Broiler Chickens

The aim of present investigation is to study the effect of single- and co-infection with REV and ALV-J on T lymphocytes bioactivities and histopathology in broiler chickens. The bioactivities of blood and spleen T lymphocytes including lymphoproliferation responses, cytotoxicitic responses, and histopathology of spleen were detected in broiler chickens singly- or co-infected with REV and ALV-J at different days post inoculation and the virus expressions in spleen of infected broiler chickens were detected with immunofluorescence assay （IFA）. The results indicated that blood and spleen T lymphocytes proliferation responses and cytotoxicity in broilers infected with REV or/and ALV-J were inhibited in the whole observed period compared with controls. In the co-infected chickens they were highly inhibited than in the single-infected. The histopathology of spleen in infected chickens at 17 and 37 d post inoculation （dpi） indicated that cell interium increased, the numbers of lymphocytes decreased, and the regrowth were destroyed or decreased, especially more significantly at 17 than at 37 dpi. The different numbers of virus were detected in spleen lymphocytes in REV- infected and/or ALV-J-infected chickens. In the spleen of co-infected chicken, both REV and ALV-J were detected and the total numbers of viruses were more than in chickens singly-infected with REV or ALV-J. Thus, the co-effect of REV and ALV-J caused more immunosuppression on T lymphocytes bioactivities in broiler chickens than single-effect of ALV-J or REV, which contributed to the sever histopathology and the product of tumor cells. This study will be helpful for understanding the effect of co-infection with many viruses and control them in poultry.

Suppressive effects of antigens on the activity of specific activated lymphocytes : A test to define the specificity of activated lymphocytes

Objective：With the regular mixed lymphocytes culture （MLC） to detect the allograft rejection, the reactivity of the activated lymphocytes （primed lymphocytes） of a recipient shows sometimes increase and sometimes decrease against the antigens from the donor, which is inconsistent with the clinical results. In order to establish a convenient method for testing the specificity of the activated lymphocytes in vitro, so as to know the rejection occurred or not by testing the existence of the specific activated lymphocytes against donor＇s HLA antigens in the recipient＇s peripheral blood. Methods： Anti-IL-2 neutralizing monoclonal antibody （anti-IL-2 N-mAb） and immunosuppressors were introduced in this test system in the presence of specific stimulators and activated lymphocytes. Results ： When the activated lymphocytes were chosen from the one-way MLC 4 d to undergo re-stimulation by specific stimulators, the activity of activated lymphocytes in the treatment group was suppressed significantly compared with that in the control group. The result of this test method is consistent with the biopsy in the clinical diagnosis of rejection. Conclusion：h suggests that the activated lymphocytes can be inactivated by specific antigens in certain conditions. This can be a useful tool to define the specificity of the activated lymphocytes.

IN VITRO ANTITUMOR ACTIVITY OF TUMOR-INFILTRATING LYMPHOCYTES FROM HUMAN GASTRIC CARCINOMA

Tumor-infiltrating lymphocytes (TIL) isolated from 11 gastric carcinoma were studied. TIL could grow for a long-term in medium containing recombi-nant interleukin-2(rlL-2). The mean expansion fold achieved in 6 long-term cultures of 11 specimens was 15.1. RIL-2 expanded gastric TIL exhibited significant cytotoxicity against K562, BGC823, MCF-7 and more effective antitumor cytotoxicity against fresh autologous tumor targets and human gastric cancer cell line. Peak cytotoxicity was shown in the third or fourth week after cultures. Cryopreservation of gastric TIL didn't influence their expansion capacity and antitumor activity. Phenotypic analysis was demonstrated in this study. The results of present study indicate that TIL from human gastric carcinoma could be expanded and reach high levels of antitumor effector function in long-term cultures with rIL-2. Their function may be of clinical importance.

Hepatitis E virus chimeric DNA vaccine elicits immunologic response in mice

AIM： To construct the plasmid pcHEV23 containing fragments of HEV ORF2 and ORF3 chimeric gene and to assess its ability to elicit specific immunologic response in mice. METHODS： The gene encoding the structural protein of HEV ORF2 fragment and full-length ORF3 was amplified by PCR. The PCR products were cloned into an eucaryotic expression plasmid pcDNA3. The resulting plasmid pcHEV23 was used as a DNA vaccine to inoculate BALB/c mice intramuscularly thrice at a dose of 100 or 200 ug. Mice injected with empty pcDNA3 DNA or saline served as control and then specific immune responses in the mice were detected. RESULTS： After 2-3 times of inoculation, all mice injected with pcHEV23 had anti-HEV IgG seroconversion and specific T lymphocyte proliferation. The lymphocyte stimulation index in the group immunized with pcHEV23 （3.1＋0.49） was higher than that in the control group （0.787±0.12, P〈0.01）. None in the control group had a detectable level of anti-HEV IgG. CONCLUSION： DNA vaccine containing HEV ORF2 and ORF3 chimeric gene can successfully induce specific humoral and cellular immune response in mice.

THE IMMUNOREGULATORY EFFECT OF TLSF_(JM) ON THE EXPRESSION OF T CELL IL-2R AND PROTEIN TYROSINE PHOSPHORYLATION

The immunoregulatory effect of TLSFJM on the expression of T cell IL- 2R and protein tyrosine phosphorylation ( PTP ) was investigated by immunohistochemistry technique. The results showed that TLSFJMcan markedly suppress the expression of IL-2R and PTP on PHA or TPA-stimulated human PBMC and murine IL-2 dependent cell line CTLL-2. However, there was no effect of TLSFJMon the production of IL-1, IL-2 and IL-6 that play an important role in the course of T lymphocyte proliferation and differentiation.

Impairment of innate immune responses in cirrhotic patients and treatment by branched-chain amino acids

It has been reported that host defense responses, such as phagocytic function of neutrophils and natural killer (NK) cell activity of lymphocytes, are impaired in cirrhotic patients. This review will concentrate on the impairment of innate immune responses in decompensated cirrhotic patients and the effect of the treatment by branched-chain amino acids (BCAA) on innate immune responses. We already reported that phagocytic function of neutrophils was significantly improved by 3-mo BCAA supplementation. In addition, the changes of NK activity were also significant at 3 mo of supplementation compared with before supplementation. Also, Fisher’s ratios were reported to be significantly increased at 3 mo of BCAA supplementation compared with those before oral supplementation. Therefore, administration of BCAA could reduce the risk of bacterial and viral infection in patients with decompensated cirrhosis by restoring impaired innate immune responses of the host. In addition, it was also revealed that BCAA oral supplementation could reduce the risk of development of hepatocellular carcinoma in cirrhotic patients. The mechanisms of the effects will also be discussed in this review article.

Skewed CD39/CD73/adenosine pathway contributes to B-cell hyperactivation and disease progression in patients with chronic hepatitis B

Background:The mechanisms underlying B-cell hyperactivation in patients with chronic hepatitis B virus(HBV)infection remain largely undefined.The present study assessed the clinical characteristics of the CD39/CD73/adenosine pathway in patients with chronic hepatitis B(CHB).Methods:We examined CD39 and CD73 expression and adenosine production by B-cells from 202 HBV-infected patients.B-cell-activation phenotypes were assessed by flow cytometry after CpG+CD40 ligand stimulation with or without blockade and activation of the adenosine pathway.Results:CD39 and CD73 expression on circulating B-cells was decreased in CHB patients with high HBV DNA,HBeAg positivity,high HBsAg levels,and active liver inflammation,and was hierarchically restored in complete responders according to HBeAg seroconversion or HBsAg reduction.However,CD39 and CD73 expression on activated memory and tissue-like memory B-cell subsets in complete responders was not increased despite effective antiviral treatments.Furthermore,CD39 and CD73 expression on intra-hepatic B-cells was decreased in inflammatory livers.In vitro,B-cells from CHB patients showed a markedly reduced capacity to generate CD39/CD73-dependent extracellular adenosine and expressed increased levels of activation markers after adenosine-production blockade.Contrastingly,metformin significantly reduced activation-marker expression via regulating AMP-activated protein kinase.Conclusions:The skewed CD39 and CD73 expression on B-cells was associated with a high viral burden,liver inflammation,and antiviral efficacy in CHB patients,and the skewed CD39/CD73/adenosine pathway contributed to B-cell hyperactivation.Regulation of the CD39/CD73/adenosine pathway using metformin may represent a therapeutic option to reverse HBVinduced immune pathogenesis.

Activated cytotoxic lymphocytes promote tumor progression by increasing the ability of 3LL tumor cells to mediate MDSC chemoattraction via Fas signaling

The Fas/FasL system transmits intracellular apoptotic signaling, inducing cell apoptosis. However, Fas signaling also exerts non-apoptotic functions in addition to inducing tumor cell apoptosis. For example, Fas signaling induces lung cancer tumor cells to produce prostaglandin E2 （PGE2） and recruit myeloid-derived suppressor cells （MDSCs）. Activated cytotoxic T lymphocytes （CTLs） induce and express high levels of FasL, but the effects of Fas activation initiated by FasL in CTLs on apoptosis-resistant tumor cells remain largely unclear. We purified activated CD8^＋ T cells from OT-1 mice, evaluated the regulatory effects of Fas activation on tumor cell escape and investigated the relevant mechanisms. We found that CTLs induced tumor cells to secrete PGE2 and increase tumor cell-mediated chemoattraction of MDSCs via Fas signaling, which was favorable to tumor growth. Our results indicate that CTLs may participate in the tumor immune evasion process. To the best of our knowledge, this is a novel mechanism by which CTLs play a role in tumor escape. Our findings implicate a strategy to enhance the antitumor immune response via reduction of negative immune responses to tumors promoted by CTLs through Fas signaling.

A NEW EXPERIMENTAL AND CLINICAL APPROACH OF COMBINING USAGE OF HIGHLY ACTIVE TUMOR-INFILTRATING LYMPHOCYTES AND HIGHLY SENSITIVE ANTITUMOR DRUGS FOR THE ADVANCED MALIGNANT TUMOR

In recent years, tumor-nfiltrating lymphocytes (TILs) have been reported to be effective for tumors in experimental and clinical research. In order to increase the therapeutical effect, we modified some steps of Rosenberg's approach a. cold digestion with collagenase at 4C for 24 hours; b. sedimentation instead of centrifugation; c. elimination of tumor cells before the cultivation procedure. Compared with the original approach, the proliferation, activity and cytotoxicity of TILs obtained by the modified procedure were much improved. TILs' expansion-old was greater than that with the original approach. Cytotoxicity against rumor cells was more potent. Increased TILs' subsets were CD3 and CD8 cells. Meanwhile, we took tumor cells from tumor tissues to test their in vitro chemosensitivities to different drugs in order to select highly sensitive antitumor drugs for treatment of cases with advanced tumors. According to the design of using highly active TILs and highly sensitive drugs (H & H therapy), preliminary clinical results of 50 cases showed higher response rates than those in treatment with TIL / IL2, LAK / 1L2 and TIL+IL2+CTX. Less toxic side effects were observed in 14 patients.

Recombinant human B7.2 IgV-like domain expressed in bacteria maintains its co-stimulatory activity in vitro

OBJECTIVE: To investigate which of the two immunoglobulin (Ig)-like domains, the immunoglobulin variable region homologous domain IgV (hB7.2 IgV) and the immunoglobulin constant region homologous domain IgC (hB7.2 IgC) on the human B7.2 molecule contains receptor binding sites, and to evaluate whether the B7.2 protein expressed in bacteria has biological activity in vitro. METHODS: Three fragments of hB7.2 IgV,hB7.2 IgC and the complete extracellular region of human B7.2 containing both the IgV and IgC domains,hB7.2 Ig (V+C), were amplified by PCR and subcloned into pGEM-Teasy. Three recombinants,pGEX-4T-3-hB7.2 IgV,pGEX-4T-3-hB7.2 IgC and pGEX-4T-3-hB7.2 Ig (V+C), were generated by cloning the fragments into a prokaryote expression plasmid (pGEX-4T-3) and transformed into the host strain E. coli DH5alpha. The relevant target fusion proteins consisting of GST and hB7.2 IgV,hB7.2 IgC and hB7.2 Ig (V+C), were identified by SDS-PAGE and Western blotting. With the presence of the first signal imitated by anti-CD3 antibody, T cell activation was observed by exposing purified T lymphocytes to each soluble form of the three bacterially-produced human B7.2 fusion proteins by [(3)H]-TdR incorporation. RESULTS: Three recombinant fusion proteins of human B7.2, GST-hB7.2 IgV, GST-hB7.2 IgC and GST-hB7.2 Ig (V+C) were produced and detected in inclusion body form from engineered bacteria. With the first signal present,T lymphocytes proliferated when co-stimulated by bacterially-produced either GST-hB7.2 Ig (V+C) or GST-hB7.2 IgV fusion proteins, but not by GST-hB7.2 IgC. CONCLUSIONS: Functional human B7.2 fusion protein can be produced in bacteria. The IgV-like domain of human B7.2 is sufficient for B7.2 to interact with its counter-receptors and co-stimulate T lymphocytes.

pcDNAL1 genetic immunization can induce specific cell-mediated immune responses in C57BL/6 mice

OBJECTIVE: To investigate the specific cell-mediated immune efficacy of the an HPV16 prophylactic vaccine. METHODS: C57BL/6 mice were randomly divided into 3 groups: experimental group I (treated with pcDNA L1), control group II (treated with pcDNA3.1) and control group III (treated with PBS buffer). The mice were immunized three times during a three-week interval. Ten to fourteen days after the third inoculation, a footpad swelling test was used to detect delayed-type hypersensitivity (DTH) responses. Antigen-specific splenocyte proliferation assay and quantitation of IFN-gamma cells in splenocytes were performed by FACS assay. RESULTS: In the experimental group, splenocytes actively proliferated after stimulation with HPV16 VLP, and had developed a markedly larger amount of CD8(+) IFN-gamma(+) cells, which is an index for special CTL. Also, the footpad was significantly thickened upon inoculation with HPV16 VLP. CONCLUSION: Naked DNA vaccine of HPV16 L1 can induce specific cell-mediated immune responses in mice, which should be considered for evaluation of HPV16 DNA vaccine feasibility.

Tumor immune checkpoints and their associated inhibitors

Immunological evasion is one of the defining characteristics of cancers,as the immune modification of an immune checkpoint(IC)confers immune evasion capabilities to tumor cells.Multiple ICs,such as programmed cell death protein-1(PD-1)and cytotoxic T-lymphocyte-associated antigen-4(CTLA-4),can bind to their respective receptors and reduce tumor immunity in a variety of ways,including blocking immune cell activation signals.IC blockade(ICB)therapies targeting these checkpoint molecules have demonstrated significant clinical benefits.This is because antibody-based IC inhibitors and a variety of specific small molecule inhibitors can inhibit key oncogenic signaling pathways and induce durable tumor remission in patients with a variety of cancers.Deciphering the roles and regulatory mechanisms of these IC molecules will provide crucial theoretical guidance for clinical treatment.In this review,we summarize the current knowledge on the functional and regulatory mechanisms of these IC molecules at multiple levels,including epigenetic regulation,transcriptional regulation,and post-translational modifications.In addition,we provide a summary of the medications targeting various nodes in the regulatory pathway,and highlight the potential of newly identified IC molecules,focusing on their potential implications for cancer diagnostics and immunotherapy.

Vitamin C promotes the proliferation and effector functions of human γδ T cells

γδT cells are of interest as effector cells for cellular immunotherapy due to their HLA-non-restricted lysis of many different tumor cell types.Potential applications include the adoptive transfer of in vitro-expandedγδT cells.Therefore,it is important to optimize the culture conditions to enable maximal proliferative and functional activity.Vitamin C(L-ascorbic acid)is an essential vitamin with multiple effects on immune cells.It is a cofactor for several enzymes,has antioxidant activity,and is an epigenetic modifier.Here,we investigated the effects of vitamin C(VC)and its more stable derivative,L-ascorbic acid 2-phosphate(pVC),on the proliferation and effector function of humanγδT cells stimulated with zoledronate(ZOL)or synthetic phosphoantigens(pAgs).VC and pVC did not increaseγδT-cell expansion within ZOL-or pAg-stimulated PBMCs,but increased the proliferation of purifiedγδT cells and 14-day-expandedγδT-cell lines in response toγδT-cell-specific pAgs.VC reduced the apoptosis ofγδT cells during primary stimulation.While pVC did not prevent activation-induced death of pAg-restimulatedγδT cells,it enhanced the cell cycle progression and cellular expansion.Furthermore,VC and pVC enhanced cytokine production during primary activation,as well as upon pAg restimulation of 14-day-expandedγδT cells.VC and pVC also increased the oxidative respiration and glycolysis ofγδT cells,but stimulus-dependent differences were observed.The modulatory activity of VC and pVC might help to increase the efficacy ofγδT-cell expansion for adoptive immunotherapy.

Uterine Natural Killer Cells:Their Choices,Their Missions

Uterine natural killer(uNK)cells,sharing many characters with peripheral blood natural killer(pNK)cells,are a major uterine lymphocyte population at early gestational stages during normal pregnancy in placental mammals. The functions of uNK cells include cytokine production and cytotoxcity that are regulated by signals through activating and inhibitory receptors.UNK cells differ from pNK cells however and contribute to the structural changes that accompany the differentiation of the maternal-fetal interface.Immunological mechanisms must provide a balanced environment for uNK cell proliferation,differentiation and activation through intricate signaling pathways.An improved knowledge of mechanisms regulating uNK cells development and the cytokine network at the maternal-fetal interface of mice and humans might be useful to harness the power of these cells for maintenance of pregnancy.Cellular & Molecular Immunology.2005;2(2):123-129.

Self-assembling, pH-responsive nanoflowers for inhibiting PAD4 and neutrophil extracellular trap formation and improving the tumor immune microenvironment

Self-assembling carrier-free nanodrugs are attractive agents because they accumulate at tumor by an enhanced permeability and retention(EPR) effect without introduction of inactive substances,and some nanodrugs can alter the immune environment. We synthesized a peptidyl arginine deiminase 4(PAD4) molecular inhibitor, ZD-E-1 M. It could self-assembled into nanodrug ZD-E-1. Using confocal laser scanning microscopy, we observed its cellular colocalization, PAD4 activity and neutrophil extracellular traps(NETs) formation. The populations of immune cells and expression of immune-related proteins were determined by single-cell mass cytometry. ZD-E-1 formed nanoflowers in an acidic environment, whereas it formed nanospheres at pH 7.4. Accumulation of ZD-E-1 at tumor was pHresponsive because of its pH-dependent differences in the size and shape. It could enter the nucleus and bind to PAD4 to prolong the intracellular retention time. In mice, ZD-E-1 inhibited tumor growth and metastasis by inhibiting PAD4 activity and NETs formation. Besides, ZD-E-1 could regulate the ratio of immune cells in LLC tumor-bearing mice. Immunosuppressive proteins like LAG3 were suppressed,while IFN-γ and TNF-a as stimulators of tumor immune response were upregulated. Overall, ZD-E-1 is a self-assembling carrier-free nanodrug that responds to pH, inhibits PAD4 activity, blocks neutrophil extracellular traps formation, and improves the tumor immune microenvironment.

Cutaneous Dengue Virus Inoculation Triggers Strong B Cell Reactions but Contrastingly Poor T Cell Responses

Dengue is a global health problem without current specific treatment nor safe vaccines available.While severe dengue is related to pre-existing non-neutralizing dengue virus(DENV)antibodies,the role of T cells in protection or pathology is unclear.Using cutaneous DENV infection in immunocompetent mice we previously showed the generation of PNA+germinal centers(GCs),now we assessed the activation and proliferation of B and T cells in draining lymph nodes(DLNs).We found a drastic remodelling of DLN compartments from 7 to 14 days post-infection(dpi)with greatly enlarged B cell follicles,occupying almost half of the DLN area compared to*24%in na?ve conditions.Enormous clusters of proliferating(Ki-67+)cells inside B follicles were found 14 dpi,representing*33%of B cells in DLNs but only*2%in noninfected mice.Inside GCs,we noticed an important recruitment of tingle body macrophages removing apoptotic cells.In contrast,the percentage of paracortex area and total T cells decreased by 14–16 dpi,compared to controls.Scattered randomly distributed Ki-67+T cells were found,similar to non-infected mice.CD69 expression by CD4+and CD8+T cells was minor,while it was remarkable in B cells,representing 1764.7%of change from basal levels 3 dpi.The apparent lack of T cell responses cannot be attributed to apoptosis since no significant differences were observed compared to noninfected mice.This study shows massive B cell activation and proliferation in DLNs upon DENV infection.In contrast,we found very poor,almost absent CD4+and CD8+T cell responses.